1. Field of the Invention
The present invention is generally related to digital pathology using line scan cameras and more particularly related to scanning fluorescent microscope samples using a line scan camera.
2. Related Art
Brightfield scanners rely on the use of sensitive color cameras such as line scan cameras or area scan cameras. Line scan cameras, which are superior to area scan cameras for digital pathology, require precise movement of the slide (and the stage upon which the slide rests) in synchronization with the data capture parameters of the camera.
The significant advantages of line scan cameras in brightfield scanning have yet to be successfully adopted with fluorescence scanners because the inherent differences between fluorescence and brightfield samples requires new techniques for automated scan and display of fluorescence samples. One fundamental difference between brightfield and fluorescence scanning is that fluorescence scanning typically uses light that is reflected off of the sample (e.g., epi-illumination) while brightfield scanning uses light that is transmitted through the sample.
In fluorescence scanning, fluorescence molecules (also called fluorochromes) are photon sensitive molecules that can absorb light at a specific wavelength (excitation) and emit light at a higher wavelength (emission). As the efficiency of this photoluminescence phenomenon is very low, the amount of emitted light is also very low. Because of the weaker signals in fluorescence scanning, a single array line scan camera typically used with brightfield scanning would be suboptimal because it would need to operate at a lower line scanning rate in order to create a high fidelity image.
Additionally, the task of finding the tissue of fluorescence samples is extremely challenging because the samples are typically transparent in brightfield illumination, which is the most efficient illumination mode in which to do tissue finding. Even more challenging with fluorescence scanning using a line scan camera is the task of automatic focus plane recognition. Another significant challenge with fluorescence scanning is determining the optimal exposure time for fluorescent samples because they vary significantly in emission intensity. Other very significant challenges related to fluorescence scanning using a line scan camera include the scanning workflow required for tissue finding, autofocus, autoexposure, multi-channel scanning (scanning samples having multiple fluorochromes with different emission wavelengths), stripe alignment, and illumination (e.g., epi-illumination). Additionally, with respect to multi-channel images, new and significant challenges are present for data management, visualization, and analysis related to the resulting image data. Therefore, what is needed is a system and method that allows for the use of a line scan camera in fluorescence scanning and overcomes the significant problems found in conventional systems as described above.